Adenoviral control of the microRNA pathway: how and why?
Wael S. Kamel
Recently an increasing attention is directed towards using viruses in cancer therapy.
One of the best viral candidates is adenovirus, since it is a relatively harmless, stable DNA virus that can be easily manipulated in the laboratory. However the biology of the adenoviral infection and how it interacts with different cellular pathways are not fully characterized and understood yet. So in this project I focused on how the adenovirus interacts with a cellular pathway called microRNA pathway. The microRNA pathway is involved in regulating more than 50% of human genes. Also it was shown previously that adenovirus can suppress this pathway, but not exactly how and why.
I investigated adenovirus growth in human cells with compromised microRNA pathway, and my results showed a moderate enhancement in virus production in these cells. This observation can indicate that the microRNA pathway can inhibit virus growth. Also I wanted to investigate further on how the adenovirus suppresses this inhibition. Upon investigating the protein levels of the main components of the microRNA pathway (Dicer and AGO2), I showed that during infection there was a rapid reduction in AGO2 protein level. On the other hand, it had been shown previously that adenovirus produces large amounts of certain viral RNA called VAI RNA, which acts mainly to suppress microRNA pathway. However it was not know if the exact sequence of VAI RNA was essential for its function. In order to investigate that, I constructed recombinant viruses in which I mutated the sequence of two different regions of VAI RNA. Upon investigating production of the viral proteins from the recombinant viruses no detectable change was observed. This can indicate that the VAI RNA acts as a competitive substrate to saturate and block the microRNA pathway in sequence independent manner. Taken all together, these results can help in understanding how adenovirus controls the host cell, which in turns can contribute in constructing more efficient adenoviral vector for cancer therapy.
Degree Project in Biology
Examensarbete i biologi, 45hp, Uppsala universitet, 2010
Biology Education Centre and the Department of Medical Biochemistry and Microbiology,
Uppsala University.
Supervisor: Göran Akusjävi
